In photoshop, I have a layer with a mask.
I want to duplicate this mask to then apply it to another layer.
How can I do that?
The easiest way to duplicate a layer mask is by holding the Alt (win) or Option (mac) key while dragging the layer mask thumbnail to another layer in the layer panel.
Here are the steps:
clickfor mac) the mask you want to copy
This is also explained on http://planetphotoshop.com/creating-and-duplicating-a-layer-mask.html
I discovered another way to duplicate a mask:
Mask is already created on the existing layer.
1) Create a new layer
2) Right-click mask on Layers tab and select 'Add Mask To Selection'
3) Go back to the new layer